The present invention relates to fan controls, and more particularly to a control and a related method for selectively controlling a direction of air flow for a cooling fan of the type capable of operating in a plurality of operating modes, including a neutral mode, a purge mode, and a cooling mode, such as for cooling a cooling core.
Farms, feedlots and other agricultural plots, as well as construction sites, mining sites and other sites, commonly produce large amounts of fine, particulate, airborne debris. These conditions present a problem for operators of agricultural vehicles such as trucks equipped with feed mixer bodies, tractors, bale pick up machines, silage baggers, composting machinery, bale grinding equipment and forage harvesters. As will be appreciated by those skilled in the art, a feed mixer body is a container having at least one agitator for mixing a plurality of livestock feeds to obtain a substantially uniform livestock feed mixture. Because these vehicles and other equipment incorporating cooling cores often operate virtually non-stop, twenty-four hours a day, the cooling cores (e.g., radiators, oil coolers, air conditioning condensers, and heat exchangers) are constantly exposed to vast amounts of particulate debris. Moreover, since cooling fans ordinarily move air through cooling cores in a single constant direction to facilitate cooling of a fluid contained within the cooling cores, the cooling cores often become clogged with debris, especially in areas having high airborne particulate matter concentrations. Consequently, upon extended use, the cooling cores fail to provide proper cooling of the fluid, and hence components associated with the cooling cores may become damaged due to overheating.
One known method for the removal of debris from the cooling cores operating in areas having high airborne particulate matter concentrations includes requiring an operator to periodically interrupt his work and manually clean out any debris deposited in the cooling core. A disadvantage of manual removal of debris is that it is time consuming and detracts from the optimal work output of the operator. However, unless the operator periodically removes the debris in such a manner, the cooling core will become clogged, which increases the likelihood that the components connected to the cooling core will become overheated and inoperable.
Another drawback of manual debris removal is that the operator must maintain a record or rely on memory as to when to periodically remove the debris from the cooling core. If the operator neglects to remove the debris, then the cooling core can quickly become clogged and cause damage to components protected by the cooling core.
Still another drawback of manual debris removal is that the operator is subjected to hazards associated with cleaning the cooling cores. For example, the cooling cores can be heated to high temperatures, and are typically in close proximity to the extreme heat of the components connected to the cooling cores, e.g., an engine.
Yet another drawback of manual debris removal is that the cooling cores are susceptible to damage by the operator as the operator removes the debris. By way of example, damage to the cooling fins of a radiator can occur during manual debris removal.
In the recreational vehicle industry there is a need for operating a fan actuating mechanism to improve cooling efficiency. In order to improve the efficiency of the cooling systems, and in particular cooling cores in recreational vehicles and the like, such vehicles are typically configured so that for each vehicle a fan is only actuated within very close temporal proximity to the time a vehicle's motor has reached a threshold operating temperature or some other threshold parameter. Otherwise, the engine will be shut down. By way of example, a typical clutch fan can be actuated by an engine electronic control module (ECM) that is actuated by one or more signals indicating a vehicle's temperature exceeds a threshold or other parameters that are hard coded into the ECM for activation when a threshold is reached. When actuated, clutch fans consume excessive power, e.g., up to about 50 horsepower. Accordingly, it is desirable to minimize the amount of time that such fans are in operation. Since the timing of the fan activation cannot be changed in the ECM by a vehicle operator without replacement of the ECM with another ECM programmed with a different timing, many manufacturers of recreational vehicles have chosen to incorporate direct drive fan systems to prevent overheating of the engine, cooling core, and other components adjacent to the cooling core. However, this is insufficient and undesirable because it continually consumes excessive power.
Variable pitch fans for cooling components are well known in the art, wherein fan blades of a variable pitch fan are capable of rotational movement to alter the pitch of the fan blade, and accordingly vary the direction of air flow through the fan blade. Examples of such variable pitch fans are disclosed in U.S. Pat. No. 6,113,351, which is incorporated herein by reference and discloses a hydraulically powered variable pitch fan. U.S. Pat. No. 6,253,716 B1, which is incorporated herein by reference, discloses a pneumatically powered variable pitch fan.
In the '716 patent, an actuator member is connected to each of the axially rotatable fan blade stems with a linkage configured so that linear movement of the actuator member causes axial rotation of the stems. The actuator member is biased to a first position by a spring. The first position represents one rotational extreme of the fan stems. A pneumatically-operated diaphragm is configured to engage the actuator member on an opposite side from the spring. Upon sufficient air pressure exerted against the diaphragm, the force exerted by the springs is overcome causing the stems to rotate to a second position. The amount of pitch may vary to achieve partial stem rotation.
Thus, there is also a need for a control for a fan that features the ability to process information received from engine sensing devices, such as ECM outputs, temperature sensors, and air conditioning pressure switches, and to signal a valve assembly or a set of relays to cause the fan to alter the direction of air flow though the cooling core.